In recent years, in the field of component analysis, optical analysis has also been carried out, in addition to analysis using chemical reactions. For example, Patent Documents 1 to 4 disclose conventional optical analysis devices for carrying out optical analysis. Also, in optical analysis, a sample is irradiated with unpolarized near-infrared light, and reflected light that was reflected by the sample or transmitted light that was transmitted by the sample is received by a light-receiving element, for example. The components in the sample are then specified based on the wavelength, intensity, and the like of received light.
In particular, Patent Document 1 discloses a blood glucose meter that measures a blood glucose level in the blood through optical analysis. The blood glucose meter disclosed in Patent Document 1 includes an optical unit configured by a light-emitting diode and a photodiode. Moreover, the blood glucose meter disclosed in Patent Document 1 is provided in a state in which blood, which is a sample, adheres to a discoidal measurement chip.
Because this measurement chip includes test paper that reacts with glucose in the blood and changes color, the blood glucose level is measured by irradiating the measurement chip with light having a specific wavelength that is emitted from the light-emitting diode, receiving light reflected by the test paper using the photodiode, and determining the intensity of the reflected light.